Rename paint data structures

ui/gfx/canvas_paint_mac.mm

Index: ui/gfx/canvas_paint_mac.mm
diff --git a/ui/gfx/canvas_paint_mac.mm b/ui/gfx/canvas_paint_mac.mm
index 73ed62abc6c348be272fb96c967c4a98454975ea..8cba450434157133ccd8c755e4f293abb4a4d6dd 100644
--- a/ui/gfx/canvas_paint_mac.mm
+++ b/ui/gfx/canvas_paint_mac.mm
@@ -23,7 +23,7 @@ CanvasSkiaPaint::CanvasSkiaPaint(NSRect dirtyRect, bool opaque)
 
 CanvasSkiaPaint::~CanvasSkiaPaint() {
   if (!is_empty()) {
-    SkCanvas* canvas = sk_canvas();
+    cc::PaintCanvas* canvas = sk_canvas();
     canvas->restoreToCount(1);
 
     // Blit the dirty rect to the current context.
@@ -68,7 +68,7 @@ void CanvasSkiaPaint::Init(bool opaque) {
 
   gfx::Size size(NSWidth(rectangle_), NSHeight(rectangle_));
   RecreateBackingCanvas(size, scale, opaque);

[danakj, 2017/01/25 19:10:07]

This is going to have to make a passthru PaintCanvas to a bitmap canvas, and
store the SkCanvas or SkBitmap here, for the destructor to use instead of it
pulling it out of sk_canvas().

[enne (OOO), 2017/01/25 21:07:16]

Why is that? gfx::Canvas creates a PaintSurface which gets a PaintCanvas off of
it and then this function will call some commands on the PaintCanvas.  This all
seems pretty straightforward to me.

[danakj, 2017/01/25 22:11:41]

Cuz the destructor does peekPixels on the canvas. I think it needs an SkCanvas
behind it.

[danakj, 2017/01/25 22:12:28]

Or more precisely, I don't think PaintCanvas should even have peekPixels so it
will need an SkCanvas* inside this class that it can call that on.

-  SkCanvas* canvas = sk_canvas();
+  cc::PaintCanvas* canvas = sk_canvas();
   canvas->clear(SkColorSetARGB(0, 0, 0, 0));
 
     // Need to translate so that the dirty region appears at the origin of the